Phosphorus-containing polymers



Patented Mar. 2, 1954 V OFFICE PHOSPHORUS-CONTAINING POLYMERS William B.McCormac signor to E. I. du Po Dany, Wilmington, ware k, Wihnington,Del., as-

nt de Nemours and Com- Del., a corporation of Dela- No Drawing.ApplicationAugust 7, 1951,

Serial No. 240,813 I 14 Claims. (climb-92.3)

This invention relates to new phosphorus-containing interpolymers and toa process for obtaining them.

In my copending application Serial No. 240,814, there are describedstable, heat-resistant polymers containing phosphorus in the form ofphosphine oxide groups. These polymers are prepared by the reaction of ahydroxyl-containing compound, such as water or an alcohol, with aphosphorus-containing interpolymer in which the phosphorus is present asdihalotertiaryphosphine groups. The latter interpolymers are the subjectof the present application. 7

It is an object of this invention to prov-ide 'polymericproductscontaining phosphorus, which polymers may readily be converted to usefulpolymers containing phosphorus in the form of the stable phosphine oxidegrouping. A further object is to provide a process for the preparationof these intermediate phosphorus-containing polymers.

According to the present invention, such interpolymers are prepared bycontacting a polymerizable organic compound containing conjugatedolefinic double bonds with a mono-substituted dihalophosphine, in thepresence of a free radical polymerization catalyst.

The polymerizable compounds containing conjugated olefinic double bondswhich are useful in the practice of this invention include hydrocarbons,such as butadiene, isoprene, 2,3-dimethyl-l,3-butadiene, 1,3-pentadiene,2,4-hexadiene, 2,4-heptadiene, 2,5-dimethyl 2,4-hexadiene, myrcene,allo-ocimene, 2,6-dimethy1-1,3-heptadiene, l,3'-decadiene, 2 phenyl 1,3butadiene, 2,3-diphenyl 1,3 butadiene, 2 benzyl-LB-butadiene,1,1-biscyc1ohexenyl, 2 tolyl 1,3 butadiene, 1- vinyl l-cyclohexene,1,2-dimethy1enecyclohexane, 1,3,5-hexatriene, 1,3-cyclopentadiene and1,3-cyclohexadiene; carboxylic acids, such as 2,4- pentadienoic acid(beta-vinylacrylic acid), sorbic acid, muconic acid and eleostearicacid, andthe esters of such acids; halogenated hydrocarbons such as2-chloro-1,3-butadiene, 2-bromo-1,3-butadiene, 1-chloro-1,3-butadieneand the like; and nitriles, such as l-cyano-l,3-butadiene(betavinyl-acrylonitrile) and 2-cyano-1,-3-butadiene. The term olefinicdoublebond is meant to include any non-aromatic carbon-to-carbon doublebond, whether occurring in an acycylic or in a cycloaliphatic system.Preferred compounds of this class are butadiene, isoprene, 2-chloro-1,3-butadiene, 2-bromo-1,3-butadiene and myrcene. Mixtures of two or more ofthese compounds may be employed. 7

The dihalophosphine'to be used in thisprocess has the formula RPX inwhich R represents a member of the group consisting of alkyl, aryl andaralkyl radicals and X represents a member of thegroup consisting ofchlorine and bromine. The preferred phosphines arediehlorophenylphosphine and dichloro'ethylphosphine. A wide variety ofphosphine derivatives having/the general formula shown may'beemployed.Representative compounds include those in which R're'presents an' alkylgroup such as methyl, ethyl, propyl,"butyl or octyl; an aryl group such'as phenyl or alphaor beta-naphthyl; or an aralkyl'group such as benzylor phenylethyl. In general, the lower members of these classes ofradicals are most useful. "These compounds are readilyavailable fromseveral well known procedures, such as by the action of a phosphorustrihalide on a hydrocarbon in the presence of aluminum chloride, or bythe action of a phosphorus trihalide on dialkyl or diaryl mercury.'Kharas'ch in'J. Org. Chem. 14, 429 (1949) describes a process'formaking dichlor'oethylphosphine from phosphorus trichloride and leadtetraethyl. The various procedures for making these compounds aresummarized in Kosolapoff, Organophosphorus Compounds, Wiley, N. Y.(1950), chapter 3.

. The polymerization reaction is carried out with the aid of a freeradical polymerization catalyst, such as an azonitrile, or a 'dialkyl ordiacyl peroxide. The term free radical polymerization catalyst is alsomeant to include actinic radiation, and particularly ultraviolet light."The azonitrile catalysts which may be employed in this reaction arethose'set forth in detail" in United States Patent No. 2,471,959,toMadison Hunt and include alpha, alpha-azodiisobutyroi1itrile; alpha,alpha'-azobis-(alpha-methylbuty ronitrile); alpha,alpha'-azobis-(alpha-methylisocapronitrile) and the like. Suitableperoxide catalysts include the dialkyl peroxides such as di(tert-butyl)peroxides, and the diacyl peroxides such as butyryl, lauroyl and benzoylperoxides. The amount of catalyst which may be used may vary over a widerange from 0.1% by weight upwards. From 1 to 5% by weight of catalyst,based on the total weight of the monomeric reactants, is ordinarilydesirable. The azonitrilesrepresent the preferred class of catalysts.

Although the interpolymers of this invention are most eiilcientlyprepared by'the use of polymerizationeatalysts of the type described,they may also be prepared without the use of catalysts. Under suchconditions, lower-yields. and

free of substances capable lower degrees of polymerization are obtained.In my copending application Serial No. 240,807, a process is describedin which conjugated dienes are reacted with substituted dihalophosphinesunder condtions calculated to give monomeric addition products. As thereset forth, the reactions almost: always yield some polymeric products inaddition to the monomers.

The two reactants may be used in equimolecular amounts or an excess ofone reactant or the other may be used to serve asa reaction medium. Theamount of each reactant present is preferably between 5 and 95% byweight of the total amount of reactants. If the diene is present inexcess, the composition of the interpolymer will ordinarily be affectedto some extent, since the excess material can take part in thepolymerization. This is not true when the dihalophosphlne is present inexcess. Use of an excess of diene results in increased yields of polymerand in the formation of polymers of increased viscosity.. The reactionmay-be conducted. in the presence of a non-reactive medium such aspetroleum ether, cyclohexane, benzene, carbon tetrachloride, chloreformand the like. The mixture should be of converting the dihalo compoundstothe corresponding-oxides, such as water, alcohols and carboxylic acids.

when chloroform is used as the reaction medium. the polymerizationproceeds with, unusual rapidity and results in increased yields ofpolymers having higher viscosities thanpolymers obtained with the othercommon solvents. These polymers are also found to contain some chlorine,even after conversion of the dichlorotertiaryphosphine groups tophosphine oxide groups. Although the nature of this effect is notentirely understood, it appears that the chloroform in some way takespart in the polymerization reaction, possibly by forming or aiding inthe formation of cross-linkages and in chain transfer.

The polymers produced according to the present invention are white tolight brown in color and vary in form from tacky to granular solids. Bytreatment with water, alcohol or a carboxylic acid, they are readilyconverted to, polymers in which the phosphorus is present as phosphineoxide groups, as described. in copending application Serial No. 240,814.The phosphine oxide polymers are heat resistant and are useful asflameprooiing and anti-static agents for textiles and in, themanufacture of molded articles and films.

The molecular weights of the polymers, measured by osmotic pressureafter conversion ofthe dihalotertiaryphosphine groups to phosphine oxidegroups are between 10,000 and 100,000.

The polymers produced according to the present invention contain varyingamounts of phosphorus, since homopolymerization of the diene may takeplace at the same time and in competition with the interpolymerization.The extent to which the interpolymerization dominates is a function ofthe reactivities of the specific reagents under the particular reactionconditions- The phosphorus content in most cases approaches, thetheoretical value for polymers in which one mole of, dihalophosphine hasreacted with one mole of diene. This value varies with the molecularweight of the reagents and is ordinarily between and 17%. Afterconversion of dihalotertiaryphosphine groups to phosphine omde groups,the theoretical maximum phosphorus content may be as high as 26.7% (forthe converted adduct of butadiene and dichloromethylphosphine), but isordinarily between about 10 and 20%. Actually the interpolymer usuallycontains somewhat less phosphorus than the theoretical. The heatresistance and hydrophilic character of the polymers containingphosphine oxide groups increase in proportion to the amount phosphoruspresent. As little as 0.1% phosphorus confers these properties on thepolymer to a determinable extent, while at 2% phosphorus the efiect ispronounced. Interpolymers containing from about 2 to 15% phosphine(before conversion to the phosphine oxide) represent the preferred classof products made according to this invention.

The invention is illustrated by the following examples:

Example 1 A mixture of 50.0 g. (0.28 m.) of redistilleddichlorophenylphosphine, 19.1 g. (0.28 m.) of redistilled isoprenecontaining no inhibitor and 700 mg. of alpha,alpha-azobis-(alpha-methylr isocapronitrile) is warmed at about 40 C.for twenty-four hours. During this time a creamcolored solid graduallyforms. A small amount of residual liquid is decanted, and the solid iswashed with petroleum ether, then hydrolyized with water to give ayellow-orange oil and the mixture is neutralized with sodium hydroxide.This oil is separated from the aqueous layer, washed with water andtaken up in chloroform. Evaporation of the chloroform and dryingv of theresidue at C. (10 mm.) gives 19.6 g. of a clear yellow-red vitreousresin.

AnaZysis.-Calcd. for Found: P=15.5%.

Th product is therefore substantially the 1:1 hcteropolymer, obtained in37% conversion. By extraction of the aqueous hydrolysate layer withchloroform, followed by distillation, there is obtained an 18% yieldofliquid monomeric adduct boiling at 160-165 C. (2 mm Example 2 ofpolymeric residue.

Example 3 A mixture of 50 g. (0.28 m.) of dichlorophenylphosphine 50 ml.of cyclohexane, 19.1 g. (0.28 m.) of redistilled isoprene and 0.7 g. ofthe catalyst of Example 1 is warmed at 40 C. for eighteen hours. Thecream-colored solid is filtered, decomposed with methanol, diluted withwater and the insoluble polymer isolated from the water and dried at C.for three days, to give 34.5 g. of a clear, glassy, yellow-brown resin.

Example 4 A mixture 01 25 g. (0.14 m.) of dichlorophenyl phosphine in 25ml. of thiophene-free benzene, 9.55 g. (0.14 m.) of isoprene and 0.35 g.of the catalyst of Example 1 is warmed at 40 C. for eighteen hours. Thecream-colored solid is illtei'ed and treated with methanol. Theevolution of methyl chloride indicates that conversion ofdichlorotertiaryphosphine groups to phosphine oxide groups is takingplace. The mixture is diluted with water and the separated polymer isdried at 100 C. for three days to give 11.6 g. of a clear, glassy,brownish resin.

7 Example Usin a 4:1 mole ratio of reagents, a mixture of 38.2 g. (0.56m.) of isoprene, 25.0 g. (0.14 m.) of dichlorophenylphosphine in 50 ml.of cyclohexane and0.'7 g. of the catalyst of Example 1 is warmed at 40C. for eighteen hours, during which time a somewhat stringy white solidprecipitates. The mixture is filtered, hydrolyzed with Water, washed anddried to give 18.4 g. of solid interpolymer containing 15.0% phos phorus(theory for the 1:1 adduct=16.1%).

Example 6 Example 7 A mixture of 46.2 g. (0.26 m.) ofdichlorophenylphosphine, 18 of alpha,alpha-azobis-(alpha-methylisocapronitrile) and 100 ml. of cyclohexane iswarmed at 50 C. for twenty hours. The cream-colored solid which forms isfiltered, treated with methanol to convertphosphorus dihalide groups tophophine oxide groups, and diluted with water. The resulting polymer isdried to give 22 g. of resinous product, having an intrinsic viscosityin methanol of 0.14.

This run is repeated under the same'conditions except that 100 ml. ofchloroform are used in place of the cyclohexane and the reaction isconducted for seventeen hours at 40 C. The product in this case weighs47.5 g. and has an intrinsic viscosity in methanol of 0.40. It contains4.9% chlorine (after treatment with methanol and water) A third run ismade using chloroform in place of the cyclohexane and with apolymerization time of three hours at 40 C. The polymeric product isobtained in a yield of 41.3 g. and has an intrinsic viscosity of 0.27.

Example 8 A mixture of 50.0 g. (0.28 m.) of dichlorophenylphosphine in50 ml. of cyclohexane, 15,1 g. (0.28 m.) of butadiene and 0.50 g. of thecatalyst of Example 1 is warmed at 40 C. in a sealed pressure bottle fortwo days. The resulting yellow brown solid is filtered, decomposed withmethanol, and diluted with water to give an insoluble oil. Drying at 100C. gives 6.1 g. of yellow solid.

Example 9 A mixture of 100.0 g. (0.56 m.) of dichlorophenylphosphine in200 ml. of cyclohexane, 49.4 g. (0.56 m.) of 2-chlorobutadiene-l,3 and0.50 g. of the catalyst of Example 1 is warmed at 45 C. for two days andthen at room temperature for g. (0.26 m.) of isoprene, 0.5 g.

6 three more days. The light brown solid which forms is treated byfiltration, decomposition with methanol, and dilution with water to give.an

insoluble'oil, which on drying gives 40 g. of red-,

dish polymer.

Analysis.Per cent P=13.3; per cent 01:14.1-

Example 10 warming a mixture of 50.0 g. (0.28 m.) of dichlorophenylphosphine in 100 ml. of cyclohexane, 34.4 g. 0.28 m.) of2,3-dichloro-1,3-butadiene and 1 g. of the catalyst of Example 1 at 60C. for one day gives a tan solid product. This is worked up byfiltration and digestion with hot methanol until there is no furtherevidence of.

reaction. Dilution with water and drying of the resultant solid at 100C. gives 27.7 g. of a cream-colored solid.

Analysis.-Cl=52.9 P=l.7%.

Ervample 11 When a mixture of 50.0 g. chlorophenylphosphine in ml. ofcyclohexane, 18.5 g. (0.28 m.) of cyclopentadiene and 0.5 glof thecatalyst of Example 1 is warmed at 35 C. for three days, a red brownsolid slowly deposits. This solid is isolated by washing with petroleumether. and is then decomposed with methanol and diluted with water togive. about 1.2 g. of solid (dry weight), containing 11.8 P.

Extraction with chloroform of the aqueous (0.28 m.) ofydi layer from thedecomposition andconcentration gives a reddish-brown oil which on dryingin vacuo at C. gives 2.4 g. of a viscous oil containing 14.4% P.

' Example 12 A mixture of 25.0 g. (0.10m) of(p-bromophenyl)-dichlorophosphine in 50 ml. of cyclo hexane, 6.6 g.(0.10 m.) of isoprene and 0.75 g. of the catalyst of Example 1 is warmedat 40 C. for twenty hours. A dull white solid forms. It is treated byfiltration, washing with petroleum ether, decomposition with methanoland dilution with water to give an insoluble material. This is dried at100 C. to give 18.2 grof a practically White solid, containing 11.0% Pand 28.3% Br.

Example 13 Example 14 A mixture of 25.0 g. (0.19 m.) ofdichloroethylphosphine in 50 ml. of cyclohexane, 25.4 g, (0.19 m.) ofZ-brOmQ-LS-butadiene and 0.5 g. of the catalyst of Example 1 is warmedat 45 C. for twenty hours. A light tan solid polymer is formed.Filtration of the reaction mass and hydrolysis with water gives a heavyyellow oil which is separated from the aqueous layer and dried to give21 g. of a yellow-brown resin containing 12.3% P and 48.0% Br.

Example 15 A mixture of 50.0 g. (0.28 m.) of dichlorophenylphosphine and50 ml. of cyclohexane 19.1 g. (0.28 m.) of isoprene, 14.8 g. (0.28 m.)of

acrylonitrile andfifili g. of the catalyst of Example. 1 is warmed at 40C; for twenty hours. Filtration. of" the cream-colored solid polymer,conversion of the dichlorotertiaryphosphine to the correspondingphosphine oxide-with methanofi and dilution with water gives an oil.This is separated, washed with water and dried to give 20.0 g. of atransparent brownish glass, containing 15.0% P and 0.9% N.

Example 16 The process described in Example 3 is repeated, using:ultraviolet light as catalyst instead of the azonitrile catalyst. Thisgives 10.7 g. of polymeric dichlorophosphine. After conversion to thecorresponding phosphine oxide the polymer contains 15.9% P.

When 500 mg. of dibenzoyl peroxide are used as catalyst in place of theazonitrile orultraviolet light, there are produced 2.0 g. of a polymericphosphine oxide containin 14.9% P.

In the absence of any polymerization catalyst,

methanol-soluble interpolymers are obtainable by the reaction betweendichlorophenylphosphine and l-cyano-lB-butadiene, ethyl sorbate,l-(pnitrophenyl)-1,3-butadiene, 2-methoxy-l,3-butadiene, andI-acetoxy-i,3-butadiene; and by the reaction betweendichloronaphthylphosphine and isoprene.

- The interpolym'erization may be carried out at any temperature shortof the decomposition point of the chemicals involved. The lowertemperature limit is that at which the reaction becomes impracticallyslow. Temperatures from -l to 125 C. may be used, the preferred rangeordinarily being from room temperature to about 75 C. Within this range,no ceiling effect has been observed,.i. e.,. there appears to be notemperature at which the rate of depolymerization balances or exceedsthe rate of polymerization. The reaction will usually be carried out atatmospheric pressure, although higher or lower pressures may be used.

I claim:

1. The process of preparing a phosphoruscontaining polymeric additionproduct which comprises contacting a polymerizable organic compoundcontaining conjugated olefinic double bonds with a mono-substituteddihalophosphine having the formula RPXz in which R represents a memberof the group consisting of alkyl, aryl and aralkyl radicals and Xrepresents a member of the group consisting of chlorine and bromine, inthe presence of a free radical polymerization catalyst and in theabsence of substantial amounts of hydroxyl-containing compounds.

2. The process of preparing a phosphoruscontaining polymeric additionproduct which comprises contacting a polymerizable organic compoundcontaining conjugated olefinic double bonds with a mono-substituteddihalophosphine having the formula RPXz in which R represents a memberof the group consisting of alkyl, aryl and aralkyl radicals and Xrepresents a member of the group consisting of chlorine and bromine, inthe presence of chloroform and a free radical polymerization catalystand in the absence of substantial amounts of hydroxyl-containingcompounds.

3. A process according to: claim 1. in which the. polymerizable; organiccompound the group consisting of butadiene, isoprene, 2-chloro-l,3butadiene and 2-bromol,3-butadiene.

4. A process according. to claim 1 in which thepclymerizable organiccompound is butadiene.

5. A process according to claim 1 in which the polymerizable organiccompound is isoprene.

6-. A process according to claim 1 in which the polymerizable organiccompound is 2chloro-1,3- butadiene.

'2. The process of. preparing a phosphoruscontaining polymeric additionproduct which comprises contacting butadiene withdichlorophenylphosphine in the presence of a free radical polymerizationcatalyst comprising an azonitrile and in the absence of substantialamounts of hydroxyl-containing compounds.

8. The process of preparing a phosphoruscontaining polymeric additionproduct which comprises contacting isoprene with dichlorophenylphosphinein the presence of a free radical polymerization catalyst comprising anazonitrile and in the absence of substantial amounts ofhydroxyl-containing compounds.

9. The process of preparing a phosphoruscontaining polymeric additionproduct which comprises contacting 2-chloro-l,3-butadiene withdichlorophenylphosphine in the presence of a free radical polymerizationcatalyst comprising an aaonitrile and in the absence of substantialamounts of hydroxyl-containing compounds.

10. A polymeric addition product of a polymerizable organic compoundcontaining conjugated olefinic double bonds and a mono-substituteddihalophosphine having the formula RPXz in which R. represents a memberof the group consisting of alkyl, aryl and aralkyl radicals and Xrepresents a member of the group consisting of chlorine and bromine,said addition product containing at least 0.1% chemically boundphosphorus.

11. The polymeric addition pro-duct of claim 10 in which thepolymerizable organic compound is selected from the group consisting ofbutadiene, isoprene, 2-chloro-l,3-butadiene and 2-bromo- 1,3-butadiene.

12. A polymeric addition product of butadiene anddichlorophenylphosphine, said addition prodnot containing at least 0.1%chemically bound phosphorus.

13. A polymeric addition product of isoprene anddichlorophenylphosphine, said addition product containing at least 0.1%chemically bound phosphorus.

lfi. A polymeric addition product of 2-chloro- 1,3-butadiene anddichlorophenylphosphine, said addition product containing at least 0.1%chemically bound phosphorus.

WILLIAM B. MCCORMACK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,382,812 Parker Aug. 14, 1945 2,520,601 Lee Aug. 29, 1950 isselected from.

1. THE PROCESS OF PREPARING A PHOSPHORUSCONTAINING POLYMERIC ADDITIONPRODUCT WHICH COMPRISES CONTACTING A POLYMERIZABLE ORGANIC COMPOUNDCONTAINING CONJUGATED OLEFINIC DOUBLE BONDS WITH A MONO-SUBSTITUTEDDIHALOPHOSPHINE HAVING THE FORMULA RPX2 IN WHICH R REPRESENTS A MEMBEROF THE GROUP CONSISTING OF ALKYL, ARYL AND ARALKYL RADICALS AND XREPRESENTS A MEMBER OF THE GROUP CONSISTING OF FREE RADICALPOLYMERIZATION IN THE PRESENCE OF A FREE RADICAL POLYMERIZATION CATALYSTAND IN THE ABSENCE OF SUBSTANTIAL AMOUNTS OF HYDROXYL-CONTAININGCOMPOUNDS.